If we directly substitute x = 1 in the expression `(x^n-1)/(x-1)` , the result is `(1-1)/(1-1) = 0/0` . The value of `0/0` is not defined or indeterminate. In limits where the expression takes on the form `0/0` or `oo/oo` or `0^0` among many others L'Hospital's rule can be used to find the limit.

This involves replacing the numerator and the denominator with their derivatives.